Displaying the quantity of marking material remaining in a printer or copier is widely achieved in a variety of ways. Typically, the imaging device operates by marking or not marking in grid pattern, each tiny square being termed a pel. It is known to count the number of pels at which ink is printed and the usage of marking material is computed from the number counted. The amount of the beginning or full supply of ink is known and the estimated remaining ink is that amount computed by subtracting the estimated usage. The estimation formulas took into account the size of the dots printed and the characteristics of the imaging device. However, prior to the foregoing parent application, no estimation formula was known which took into account actual usage history of the imaging device.
By taking into account actual usage history, the estimation formula is made more accurate. In accordance with the preferred embodiment of this application, only single sensing for toner/ink-out is employed, which is cost effective. Since the estimation formula is dynamically modified to reflect past usage, the amount of toner or ink remaining during use after resupply of toner or ink is determined with satisfactory accuracy. This is communicated to the operator by some display, which may be a standard gauge-face (alternatively by artificial voice message, panel display after operator inquiry or similar alternatives).